Thermionic device



G. M. WRIGHT- THERMIONIC DEVICE- APPLICATION FILED MAY 1. 1918.

1,394,601. Patented 0011251921.

- STATES v enonen MAURICE WRIGHT, or LONDON,

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ENGLAND, ASSIGNOR, BY mnsnnassrcn- MENTS, TO RADIO CORPORATION OF AMERICA, 1A CORPORATION OF DELAWARE.

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Specification of Letters Patent.

Patented Oct, 25, 1%21.

Application filed May 1, 1918. Serial No. 231,872.-

To all whom it may concern: 7

Be it known that I, GEORGE MAURICE \VRIcH'r, a subject of the King of Great Britain, residing at Marconi House, Strand, London, W. C. 2, England, have invented new and useful Thermionic Devices, of which the following is a specification.

This invention relates to the employment of thermionic devices or relays of the type comprising a filament (acting as a cathode), a grid "and an anode, for the purpose of magnifying electric currents or differences of potential.

In some cases it has beenfound impossible to produce with one such relay sufiicient magnification, and in consequence two or more relays have been used. Such a succession of relays, however, involves a great complexity of circuits, and it is difficult to control the reactions in the whole apparatus.

The object of this invention is so to arrange a'succession of these thermionic rela s that the strength of atmospheric distur ances is reduced while at the same time an desired magnification can be obtained wit great simplicity of circuits.

In the accompanying drawing, I have illustrated one embodiment of my invention.

According to this invention to the anode of a thermionicrelay is connected one end of a high resistance, preferably of the order of the resistance of the relay itself, and the other end thereof is connected to the positive pole of a high tension battery the negative of which is connected to the filament. The j unction between the anode and the resistance is connected to the grid of a second relay the filament of which is connected to a point in r the battery which is at the same potential as,

or, alternatively at any desired small potential difference from, the said junction. The anode and filament of the said second relay are similarly connected through a high resistance and battery. The junction between the anode of this second relay and its resistance and a point in the battery may be similarly connected to the grid and filament respectively of the next relay, and so on.

When therefore the gridand filan ent of the first relay are connected in an initlal circuit so that the potential of the grid with reference to the filament; \is varied in any way, a corresponding variation is caused in theresistance of the space between theanode and the filament which causes a magnified tween the junction and the point in the battery connected to the second filament. This difference of potential is again magnified by the second relay, and so on.

The figure shows a thermionic device in accordance with this invention, f being the filament, a the anode and g the grid which is interposed between them, while connected to the anode is a high resistance r. H is a. high voltage battery having its negative terminal connected to the filament battery I) and its positive terminal confected to the resistance'r. For the purpose of maintaining the correct potential between the grid and thefilament, the oscillator circuit L C is connected to the grid 9 an the potentiomearound the anode circuit a 1' H f and there will be a certain drop of potential along the resistance 1' and a certain drop from anode to filament'of the relay making it possible tofind a point m on the battery H such that there Will be no potential difference between m and the point a, or it is possible by selection of m to make this potential difference any required value within limits.

' Now if the potential of the grid 9 with reference to the filament f be varied, the current in the anode circuit a r H 7 will vary accordingly, which is equivalent to a variation of internal resistance, and this varying current will cause corresponding variations in the potential difference between ,m and n. This latter variation is applied to the grid and filament of a second relay similarly connected and the series may be continued as far as desired. The figure showsa succession of three relays in which the magnified variations of potential applied to the grid of the last relay cause a' a magnified oscillatory current to flow inthe circuit L C While at the same time magnifying weak signals the apparatus also has the property of reducing the strength of atmospheric disturbances. Normally the relays are operated in such a condition that the current in their respective rid circuits is negligible, but if the variations of potential of n with regard to m are so large that a current is *caused to flow ,from 'n to m across the gridfilament space of the second relay, then a limiting action takes place. Immediately this current begins to flow the potential difference between n and m will be reduced thereby. Since each relay will pass current only in the direction from grid to filament, the second of the series will reduce impulses above a certain strength such as to tend to.

make n positive with regard to m. This limiting action will not occur when the impulse is such as to make at negative with regard to m and when this is the case n will become positive to m and the current from n to m across the grid-filament space of the third valve will effect the reduction of potential difference between n and m Accordingly with two valves connected as ferred to is an oscillatory circuit coupled to the aerial and the potential difference across the junction and the corres onding point in the battery of the last re ay acts upon a tuned circuit and produces oscillations therein which may be detected in any of the well known ways.

What I claim is 1. The combination of a thermionic relay having a cathode, grid and anode, a resistance connected to the anode thereof, a battery connected to the resistance and to the cathode of the relay, and a second thermionic relay having a cathode, grid and anode having its grid connected to the anode of the first and its cathode to a point in the battery between its terminals.

2. The combination of a thermionic relay having a cathode, grid andianode, a resistance connected to the anode thereof, a battery connected to the resistance and to the the resistance and its cathode to a point in the battery which is at the same potential as the said junction.

3. The combination of a thermionic relay having a cathode, grid and anode, a resistance connected to the anode thereof, a battery connected to the resistance and to the cathode of the relay, a second thermionic relay having a cathode, grid and anode having its grid connected to the anode of the first and its cathode to a point in the battery between its terminals, asecond resistance connected to the anode of the second relay and a second battery connected to the second resistance and to the cathode of the second relay.

4. The combination of successive thermionic relays, each having a cathode, grid and anode, and each relay except the last having a resistance connected to its anode and a battery connected to the resistance and to its cathode, and each relay after the first having its grid connected to the anode of the preceding relay and having its cathode connected to a point between the terminals. of the battery of the anode circuit of the preceding relay.

5. The combination of successive thermionic relays, each having a cathode, grid and anode, and each relay except the lasthaving a resistance connected to its anode and a. battery connected to the resistance and to its cathode, and each relay after the first having its grid connected to the junction between the anode of the preceding relay and the resistance and having its cathode connected to a point in the battery of the anode circuit of the preceding relay which is at substantially the same potential as the said junction.

In testimony that I claim the foregoing as my invention, I have signed my name this 10th day of April, 1918.

GEORGE MAURICE WRIGHT. 

